Maybe some, but most weigh in close to 200lbs and rehydrate to (far) above it. Okay. Catchweight was the wrong word, but my point is: if a great smaller guy want to step up to heavyweight, there will be big money because everyone wants to see the smaller underdog upset the unwritten rules of boxing, i.e. bigger is better. Sanctioning bodies only listen to one thing, and that is money, and where there is money, they will sanction it, 187 or 193lbs, no problem.
I do think the nature of boxing as a profession and its progression (regression?) over the years does affect the development of its athletes. In many other sports, seasons have become longer and the sport itself more financially rewarding, allowing more participants to compete more often at a very high level (pro baseball, football, hockey, tennis, etc. players no longer need day jobs; elite level track athletes are better supported). In boxing, athletes now compete less (fewer fights) and the competition has become more watered down as there are fewer competitors (many better ways to make a decent living). The elite level compete less than in the past and against fewer quality opponents (it has also become more difficult to make matches between elite level opponents due to the nature of the business). Training and nutrition increases likely don't balance out against the loss in "honing of the skills".